1. Field of the Invention
The present invention relates to a paper feeder for an image forming apparatus.
2. Description of the Related Art
Some paper feeders for image forming apparatuses each are provided with a first paper cassette and a second paper cassette located upstream of the first paper cassette in a paper feed path and configured to transport paper fed from the second paper cassette along a paper guide formed by utilizing a portion of the shape of the first paper cassette downstream of the second paper cassette. Such a paper feeder has the following problem: when the first paper cassette is pulled out before a sheet has been transported from the second paper cassette, absence of the paper guide can cause the sheet to fail to pass through the second paper cassette, and eventually a paper jam.
As techniques for preventing such a paper jam, the following methods have been proposed: a method of causing a locking mechanism utilizing a solenoid to prevent the first paper cassette from being pulling out (Japanese Patent No. 2542064); a method of, when the first paper cassette is pulled out to replace paper, rotating another paper guide mechanism (auxiliary paper guide) to thereby set a paper transport path formed with the auxiliary paper guide in place of a paper transport path formed with the first paper cassette (Japanese Patent Application Laid-open No. H5-740); and a method of, when a detecting mechanism detects that the first paper cassette is removed, a central processing unit (CPU) stops sheet feeding from the second paper cassette (Japanese Patent Application Laid-open No. H11-240648).
However, any one of the methods of the conventional art is disadvantageous in that the number of parts increases due to the additional locking mechanism, paper guide mechanism, or detecting mechanism, which increases manufacturing cost.